Advanced printing systems, e.g., recently developed ink jet printer systems, are capable of running at higher speeds and using lighter weight materials. Due to the increased running speeds and lighter weight materials, a registration system capable of handling these conditions is required.
Cross roll systems offer registration accuracy at increased speeds; however, cross roll registration systems are susceptible to sheet damage at the lead edge when the incoming registration allows the sheet to impact into the cross roll registration edge, e.g., an alignment stop. This issue is particularly relevant when using lightweight media. It has been found that lightweight media sheets do not have the beam strength required to prevent buckling as each sheet is registered against a solid registration edge, e.g., an alignment stop. This issue often presents in the form of a curled corner at the lead edge due to the corner being the first impact location of the sheet against the solid registration edge.
Current designs of cross roll systems show excellent registration within a reduced subset of media. It is well known that, because cross roll systems register a sheet against a solid registration wall the theoretical error is quite small. Studies of various non-cross roll registration systems show that the capabilities of cross roll systems can exceed the performance of those systems.
Even if the forces on the cross rolls are controlled for various paper weights, the sheets are still at risk of being damaged. This can be attributed to the fact that cross roll registration systems, as standalone systems, do not control the extent of skew of the sheet or initially register the sheet so that the sheet contacts the registration wall at an optimum angle or optimum position to reduce damage to the sheet.